1. Field
Apparatuses consistent with exemplary embodiments relate to a backlight unit and a holographic display apparatus including the backlight unit, and more particularly to a beam steering backlight unit providing a hologram image to multiple viewing zones and a holographic display apparatus including the beam steering backlight unit.
2. Description of the Related Art
Methods of displaying 3D images such glasses-type methods and non-glasses-type methods are widely used. Examples of glasses-type methods include deflected glasses-type methods and shutter glasses-type methods, and examples of non-glasses-type methods include lenticular methods and parallax barrier methods. These methods operate according to the principle of binocular parallax, and increasing the number of viewpoints is limited. In addition, these methods may cause viewer fatigue due to the difference between the depth perceived by the brain and the focus of the eyes.
Recently, holographic display methods, which are 3D image display methods capable of making the depth perceived by the brain consistent with the focus of the eyes and of providing full parallax, have been gradually put to practical use. According to a holographic display technique, when reference light is irradiated onto a hologram pattern having recorded thereon an interference pattern obtained by interference between object light reflected from an original object and the reference light, the reference light is diffracted and an image of the original object is reproduced. When a currently commercialized holographic display technique is used, a computer-generated hologram (CGH), rather than a hologram pattern obtained by directly exposing an original object to light, is provided as an electric signal to a spatial light modulator. Then, the spatial light modulator forms a hologram pattern and diffracts reference light according to the input CGH signal, thereby generating a 3D image.